4-VECTOR CORRELATION EXPERIMENT ON NE(3P)- MEASUREMENTS ON INTRAMULTIPLET MIXING(HE COLLISIONS )

Intramultiplet mixing collisions have been investigated using polarize d Ne(3p) atoms with a well-defined initial relative velocity, i.e., tw o initial-state vectors. By analyzing the final-state center-of-mass v elocity with a (Doppler-detuned) probe laser with a well-defined polar ization and detecting the laser-induced fluorescence we measure the di fferential cross section and the polarization of the final state, i.e. , two final-state vectors. Measurements have been done at a collision energy E = 70 meV, for both the alpha(7) and alpha(9) (Paschen numberi ng) initial states. For the elastic alpha(7) --> alpha(7) collisions t he experimental results are strongly hindered by the undesired respons e on elastic scattering of the metastable Ne(3s,P-3(0)) state. Inelast ic collisions have been investigated for the alpha(9) state, that form s a closed level system with the metastable Ne(3s,P-3(2)) state. For t he alpha(9) --> alpha(8) transition experimental results are presented for both parallel and perpendicular orientations of the polarizations of the pump and probe laser, respectively, as well as for circular po larized (sigma(+),sigma(+)) and (sigma(+),sigma(-)) configurations. Th e experiments are compared to a full quantum-mechanical coupled channe ls calculation of the scattering process, using the model potentials o f Hennecart and Masnou-Seeuws as input. The output of this calculation is combined with a density matrix description of the initial-and fina l-state polarization. Both shape of the differential cross sections an d their relative scaling for different laser polarization configuratio ns agree well with experiment. This gives strong support for the quali ty of the model potentials used.